Polymer mixture for slush molding

ABSTRACT

A mixture of elastomeric thermoplastic compositions which includes, on a weight percentage basis, (A) from 40 to 90% of a heterophasic polyolefin composition having a melt flow rate measured according to ASTM-D 1238, condition L, ranging from 20 to 100 g/10 min; and (B) from 10 to 60% of a heterophasic polyolefin composition that is partially dynamically crosslinked. The powders of this mixture are used in slush molding process for the production of laminated products.

BACKGROUND OF THE INVENTION

This application is a U.S. national stage of international applicationPCT/EP99/06329, filed Nov. 13, 1997.

The present invention concerns a mixture of thermoplastic andelastomeric polyolefin compositions; the mixture is partiallycross-linked, and has in spite of this a good melt flow rate.

The mixtures of the present invention are particularly suitable for theproduction of laminated articles produced by way of the slush moldingprocess. In particular, the mixtures are used for the production ofsynthetic leather to be used, for example, in the automotive industry tocover some of automobile parts.

Synthetic leathers produced from thermoplastic polyolefins are alreadyknown in the art. For example, published European patent applicationEP-A-633 289, on behalf of Himont Incorporated, describes the use ofpartially cross-linked thermoplastic and elastomeric polyolefincompositions to be used in a slush molding process for the production ofsynthetic leathers. Said compositions have good mechanical properties,such as high elongation at break values, therefore the laminatesobtained from them are adequate for use in thermoforming processes.However, these compositions present the problem of having a low meltflow rate, and consequently a number of pinholes form in the laminatesproduced by slush molding.

Moreover, published European patent application EP-A-637 610, on behalfof Himont Incorporated, describes thermoplastic polyolefin compositionssuitable for the production of very soft synthetic leathers using aslush molding process. The leathers produced from these compositions donot have high tensile strength and elastic recovery values.

Patent application WO 95/35344 (Reydel) also describes compositions forthe production of synthetic leather by way of slush molding. Thesecompositions comprise a heterophasic matrix made of a crystallinepropylene polymer and a propylene/ethylene rubber with a small contentof ethylene. In order to facilitate the removal of the leathers from themold and prevent the surfacing of low molecular weight rubbery particlesthat cause problems related to sticking as well as soiling the mold,said compositions also contain a resin comprising a rubber, EPR or EPDM,either cross-linked or not cross-linked. However, in order to achievethe desired properties, such as specific levels of softness of thefinished product and melt flow rate, all the compositions cited in saidpatent application contain extender oil, as is proven by our analysesand demonstrated in the comparative examples.

Moreover, the exemplified compositions of the above mentioned patentapplication WO 95/35344, according to measurements we carried out whichare demonstrated in the comparative examples, present tensile strengthand elongation at break values that are not completely satisfactory.Good values related to said properties are important in order to preventlacerations of the laminate when it is being removed from the mold.

BRIEF SUMMARY OF THE INVENTION

Now it has been found that it is possible to produce, by using the slushmolding process, laminated articles with a good degree of softnessalthough they do not contain extender oil. Without the extender oil, thequantity of low molecular weight material that is exuded by the laminateover time, which causes fouling and fogging, is considerably reduced,and also eliminated is the undesirable shiny and oily appearance of thelaminate that is caused by the surfacing of said oil.

It has also been found that by using the mixtures of the presentinvention it is possible to produce, by way of slush molding, laminateswith a reduced number of pinholes and reduced size of said pinholes,both on the surface, particularly the surface that is in contact withthe mold, and in the inner part of said laminates. In order to achievesaid result one needs a good melt flow rate of the polymer. In fact, agood melt flow rate, together with a good flowability of the polymerpowder that is typical in slush molding processes, allows for ahomogeneous and fast distribution of the polymer in the mold; therefore,the creation of voids that cause the formation of pinholes of varioussizes in the laminate is reduced considerably, thus improving theappearance of the laminate, which would otherwise be marred by thepresence of a number of big pinholes on the surface. Moreover, saidpinholes are even more undesirable since usually they form also on theinside of the laminate thus reducing the mechanical properties of saidlaminate such as a decreased tensile strength.

In order to avoid said inconveniences a laminate has been produced frompowders of a mixture of elastomeric thermoplastic compositions, saidcompositions containing polymer fractions having a viscosity that issufficiently low to allow, in spite of the presence of partiallycross-linked rubber, a good flow of the melt mixture during the fillingof the slush-molding mold. Due to its melt flow, the mixture spreadsmore homogeneously, thus reducing first of all the size and number ofvoids and consequently of the pinholes in the laminate.

Although the mixtures of the present invention have low viscosityvalues, they do cause some limited fogging and stickiness to occur.

An additional advantage is the fact that the laminates obtained fromsaid mixtures have good mechanical properties; in particular, they havetensile strength and elongation at break values that confer to thelaminates good tensile strength as well as making them deformationproof. Said characteristics make it possible to remove the laminatesfrom the molds without damaging them.

Therefore, object of the present invention is a mixture of elastomericthermoplastic compositions comprising (weight percentage):

A) from 40 to 90%, preferably from 60 to 80%, of a heterophasicpolyolefin composition (A) having a melt flow rate (measured accordingto ASTM-D 1238, condition L) ranging from 20 to 100 g/10 min, preferablyfrom 30 to 60 g/10 min; and

B) from 10 to 60%, preferably from 20 to 40%, of a partially dynamicallycross-linked heterophasic polyolefin composition (B).

BRIEF SUMMARY OF THE INVENTION

Heterophasic polyolefin composition refers to a composition comprisingpolymers of the CH₂═CHR olefins, where R is hydrogen or a C₁-C₈ alkylradical; the composition comprises both crystalline and amorphouselastomeric polymers.

By definition “partially cross-linked” it is meant that to the degree ofcross-linking in terms of the content of gels with respect to the weightof the fraction of elastomeric copolymer soluble in xylene at ambienttemperature (i.e. about 25° C.) before cross-linking, is preferably lessthan or equal to 70%, more preferably less than 50%, from 3% to 45% forexample. The gels content corresponds to the fraction of elastomericcopolymer that is rendered insoluble by cross-linking.

Preferably heterophasic compositions (A) and (B) are obtained from abasic composition comprising the following polymer fractions (parts andpercentages by weight):

a) 10-40 parts, preferably 20-40, of an isotactic propylene homopolymerhaving an isotactic index greater than 80, preferably greater than 90,or a propylene random copolymer with ethylene and/or a C₄-C₁₀ α-olefinof formula CH₂═CHR, where R is a C₂-C₈ alkyl radical; said copolymercontaining greater than 80% of propylene and having an isotactic indexin boiling heptane greater than 80;

b) 0-20 parts of a copolymer fraction containing ethylene, insoluble inxylene at ambient temperature; and

c) 40-95 parts, preferably 60-80, of a copolymer fraction of ethylenewith propylene and/or a C₄-C₁₀ α-olefin of formula CH₂═CHR, where R is aC₂-C₈ alkyl radical, and optionally with a small quantity of diene; saidfraction, soluble in xylene at ambient temperature, contains ethylene inquantities less than or equal to 35%, preferably from 15 to 30%.

Examples of the above mentioned basic composition are described inEuropean patent application EP-A-0 472 946 published on behalf of HimontIncorporated.

Preferably the content of ethylene in fraction (b) is equal to orgreater than 75% by weight, more preferably greater than or equal to 80%by weight, with respect to the overall weight of (b).

For example fraction (b) is a semicrystalline essentially linearcopolymer of ethylene, and in addition to the ethylene, it containspreferably the same α-olefins present in fraction (c). When present, itis preferable that the quantity of said fraction be greater than 1 partby weight.

The total quantity of copolymerized ethylene in the basic compositioncan vary, for example, from 15 to 35% by weight.

The quantity of diene in fraction (c) ranges preferably from 1 to 4% byweight. Specific examples of the above mentioned dienes are:1,3-butadiene, 1,4-hexadiene, 1,5-hexadiene, and5-ethylidene-2-norbornene.

The above mentioned basic composition can be prepared by mixingcomponents (a), (b), and (c) in the molten state, i.e., above their meltor softening temperature, or by way of sequential polymerization in twoor more stages in the presence of a highly stereospecific Ziegler-Nattacatalyst. In particular the catalyst system comprises (i) a solidcatalyst component containing a titanium compound and an electron-donorcompound both supported on a magnesium halide and (ii) an Al-trialkylcompound and an electron-donor compound.

Examples of sequential polymerization processes are described in theabove mentioned european patent application EP-A-0 472946. If saidcomponent (b) is present, it is preferable that the (b)/(c) weight ratiobe less than 0.4, in particular from 0.1 to 0.3. Moreover, it ispreferable that the weight percentage of fraction (c) with respect tothe total weight of the heterophasic composition, range from 50 to 90%,in particular from 65 to 80%.

The mixtures of the present invention that can be obtained from theabove mentioned basic composition are the preferred ones. Saidelastomeric thermoplastic compositions mixtures comprise:

1°) a heterophasic polyolefin composition (A) comprising the followingpolymer fractions (parts and percentages by weight):

a) 10-40 parts, preferably 20-40, of an isotactic propylene homopolymerhaving an isotactic index greater than 80, preferably greater than 90,or a propylene random copolymer with ethylene and/or a C₄-C₁₀ α-olefinof formula CH₂═CHR, where R is a C₂-C₈ alkyl radical; said copolymercontaining greater than 80% of propylene and having an isotactic indexin boiling heptane greater than 80; said fraction having an intrinsicviscosity ranging from 0.8 to 1.3 dL/g;

b) 0-20 parts of a copolymer fraction containing ethylene, insoluble inxylene at ambient temperature; and

c) 40-95 parts, preferably 60-80, of a copolymer fraction of ethylenewith propylene and/or a C₄-C₁₀ α-olefin of formula CH₂═CHR, where R is aC₂-C₈ alkyl radical, and optionally with a small quantity of diene; saidfraction, soluble in xylene at ambient temperature, contains ethylene inquantities less than or equal to 35%, preferably ranging from 15 to 30%;and

2°) a partially dynamically cross-linked heterophasic polyolefincomposition (B) comprising the following polymer fractions (parts andpercentage by weight):

i) 5-50 parts, preferably 5-35, of an isotactic propylene homopolymerhaving an isotactic index greater than 80, preferably greater than 90,or a propylene random copolymer with ethylene and/or a C₄-C₁₀ α-olefinof formula CH₂═CHR, where R is a C₂-C₈ alkyl radical; said copolymercontaining more than 85%, preferably more than 95%, of propylene, andhaving an isotactic index in boiling heptane greater than 80; saidfraction having an intrinsic viscosity ranging from 0.15 to 0.6 dL/g;

ii) 50-95% parts, preferably 65-95, of an elastomeric polymer fractionpartially cross-linked and partially soluble in xylene at ambienttemperature, containing ethylene, propylene, and/or a C₄-C₁₀ α-olefin offormula CH₂═CHR, where R is a C₂-C₈ alkyl radical, and optionally asmall quantity of diene;

said composition (B) comprising from 20 to 92, preferably from 40 to80%, of a fraction (I) soluble in xylene at ambient temperature, andcontaining ethylene, propylene, and/or a C₄-C₁₀ α-olefin of formulaCH₂═CHR, where R is a C₂-C₈ alkyl radical, and optionally a smallquantity of diene, where the ethylene is present in fraction (I) inquantities less than or equal to 35%, preferably ranging from 15 to 30%,more preferably from 20 to 30%.

More preferably fraction (a) of composition (A) has an intrinsicviscosity ranging from 0.9 to 1.2 dL/g.

More preferably fraction (a) of composition (B) has an intrinsicviscosity ranging from 0.2 to 0.5 dL/g.

The flow rate of the powders of the mixture of the present invention isobtained both by way of known technologies, whereby one obtainsregularly formed powders of reduced size and having size fairly uniform,as explained below in more details, and by the lack of stickinessexhibited by the powders produced with the mixtures of the presentinvention.

The desired intrinsic viscosity for compositions (A) and (B) can beobtained, for example, by way of a chemical cracking process of thepolymer chain to which the composition is subjected. The chemicalcracking process is carried out by using known techniques. One of saidtechniques is based on the use of peroxides which are added to thepolymer composition in quantities sufficient to obtain the desireddegree of viscosity and/or molecular weight. The peroxides that are mostconveniently used for the chemical cracking process of polymercompositions have a decomposition temperature that preferably rangesfrom 150 to 250° C. Examples of said peroxides are di-tert-butylperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexene,and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, which is sold under thetrade-name Luperox 101. The quantity of peroxide necessary for thedegradation process preferably ranges from 0.05 to 5%, more preferablyfrom 0.5 to 1%, by weight with respect to the polymer.

Composition (B) is obtained by cross-linking the above mentioned basiccomposition. Generally speaking, any cross-linking agent known in theart can be used for the preparation of cross-linked composition (B). Inparticular one can use as cross-linking agents the organic peroxidesthat have, for example, a half-life ranging from 3 to 20 minutes,preferably from 7 to 18 minutes, at 160° C. Specific examples ofperoxides are: 1,1′-bis(tert-butylperoxy)diisopropylbenzene, dicumylperoxide, butyl-4,4′-bis(tert-butylperoxy)-valerate,2,5-di(tert-butylperoxy)-2,5-dimethylhexane. The peroxides are generallyused in quantities ranging from 0.5% to 5%, preferably from 1 to 3%, byweight with respect to the total weight of the composition that issubjected to cross-linking.

Together with the peroxides one can use a cross-linking coadjuvant.Preferred examples of coadjuvant are the 1,2-polybutadienes, triallylcyanurates, triallyl isocyanurates, ethylene glycol dimethylmethacrylate, divinylbenzene, and furan derivatives of formula

where X is a —CHO, —COOH, —CHONH, —CN, —NO₂, —CH₂—CO—CH₂—COOR, or—CH(COOR)₂, where R is a C₆-C₈ aryl or C₁-C₄ alkyl, n is 1 or 2, R¹ andR², equal or different, are hydrogen, C₁-C₄ alkyl, C₅-C₈ cycloalkyl.

Generally the 1,2-polybutadienes have a molecular weight of at least1300, preferably ranging from 2400 to 13000. The content of vinyl groupsin configuration 1,2 is preferably equal to or greater than 50%, inparticular from 50 to 90%. One specific example is the Lithene Ph (byRevertex).

The composition (B) used in the present invention is subjected to adynamic cross-linking process. Said process consists of subjecting thebasic composition to a mixing process at temperatures equal to orgreater than the softening or melting temperature of composition (B) inthe presence of a cross-linking agent, which can be added before,during, or after the first mixing phase, and continuing said mixing evenduring the cross-linking phase. The mixing can be carried out, forexample, in an internal mixer (Banbury type) or in a twin screw and/orBuss extruder, or in a system which combines the two.

The dynamic cross-linking process is carried out for a period of timethat can vary, preferably ranging from 40 seconds to 6 minutes, and at atemperature that preferably ranges from 140 to 220° C.

An indirect evaluation of the degree of cross-linking can be estimated,as indicated above, by the quantity of gels that form due to thecross-linking which reduce the solubility of component (C) of theinitial composition. Said quantity is calculated using the followingformula:

% gel=(C−X)·(1/C)·100

where C is the percentage of component (C) in the initial composition,while X is the soluble fraction of the partially cross-linkedcomposition. In said formula, the solubility contribution of component(A) in the initial composition is overlooked since it is very nominalcompared to that of component (C).

Preferred examples of polyolefin compositions (B) that can be used forthe production of the mixture of the present invention are cited in theabove mentioned European patent application EP-A-633 289, whosedescription is incorporated herein for reference.

To the mixture of the elastomeric thermoplastic compositions of thepresent invention one preferably adds a substance that increases furtherthe flow rate of the powder, such as silica, in quantities ranging from0.5 to 2% by weight.

Moreover, the mixture of the elastomeric thermoplastic compositions ofthe present invention can also contain the usual substances that arepresent in the polyolefin compositions comprising elastomers that areadded to compositions subjected to mixing and cross-linking, such as forexample mineral fillers, plasticizing agents, carbon black, pigments,and stabilizing agents.

The above mentioned heterophasic compositions (A) and (B), andoptionally other components, are mixed in the above mentionedproportions using known equipment, such as a Banbury, a Buss, or asingle-screw and/or double-screw extruder. Subsequently the mixture issubjected to milling at very low temperatures, using liquid nitrogen asthe cooling medium, for example, until it is reduced to a powder. Foruse in the slush molding process it is preferable that the powders ofthe polyolefin composition of the present invention have a regular form.It is also preferable that they have a narrow particle size distributionand a small diameter. In particular, it is preferable that the diameterof the particles be less than 500 μm, preferably less than 350 μm, morepreferably not more than 5% by weight of the particles have a diametergreater than 300 μm, more preferably 250 μm. For example, one can use apowder where not more than 5% by weight of the particles have a diametergreater than 250 μm, and 50% by weight of the particles have a diameterranging from 150 to 160 μm, for example.

The powders obtained from the mixture of the present invention are usedin slush molding processes. The process technologies and methods usedare those traditionally known and utilized, for example, for theproduction of polyvinyl chloride.

One of the examples describing the process where the mixtures of thepresent invention are used comprises the following steps:

I) heating of the mold (in an oven, for example) to a temperatureranging from 200 to 280° C.;

II) introduction of the polyolefin composition powders in the mold andsubsequent melting of the powders;

III) further melting of the outer surface of the polymer sheet thatformed in the mold of step (II), by way of postheating (in an oven forexample), in order to eliminate possible surface irregularities; and

IV) cooling and removal of the laminate thus obtained.

The product can be used as is in the form of synthetic leather, or canbe subjected to further treatments, such as painting and lacquering.

The following examples are given in order to illustrate but not limitthe present invention.

The data relative to the properties of the products, the mixtures, thecompositions, and the specimens obtained in the examples and comparativeexamples have been determined by way of the following methods:

Melt Flow Rate (MFR): ASTM-D 1238

Solubility in xylene: (see Note 1 below)

Number of pinholes per surface unit: (see Note 2 below)

Average pinhole diameter: (see Note 2 below)

Maximum pinhole diameter: (see Note 2 below)

Flexural modulus of elasticity: ASTM D-790

Shore A Hardness: ASTM D-2240

Compression set: ASTM D-395, method B

Tensile strength: ASTM D-412

Elongation at break: ASTM D-412

Fogging Test: DIN 75201

Note 1. Determination of the percentage soluble in xylene: one preparesa solution of the sample in xylene at a weight concentration of 1%,keeping the sample in xylene for one hour at 135° C. while stirring.Continuing to stir the content is allowed to cool to 95° C., after whichthe solution is poured in a 25° C. bath, and left there for 20 minuteswithout stirring, and for an additional 10 minutes while stirring. Thesolution is then filtered, and acetone is added to a portion of thefiltrate in order to obtain the precipitation of the dissolved polymer.The polymer thus obtained is then recovered, washed, dried, and thenweighed in order to determine the percentage soluble in xylene.

Note 2. Determination of the number of pinholes per surface unit, andthe average and maximum pinhole diameter: the number of pinholes hasbeen determined by counting the pinholes per surface unit from aphotograph of the leather obtained with a Wild stereo microscopeoperating in reflection at a 20× enlargement. The determination of theirdimension was done assuming that the surface of the pinhole section iscircular. The maximum diameter of the largest pinhole was measured, andthe average diameter of the pinholes was calculated mathematically.

The compositions used in the examples and the comparative examples areas follows:

I) Heterophasic composition, where the MFR is 0.6 g/10 min, comprising(weight percentage):

a) 33% of a crystalline propylene random copolymer with 4.3% ofethylene; 9% of the copolymer is insoluble in xylene at 25° C., and itsintrinsic viscosity [η] is 1.5 dL/g;

b) 6% of an ethylene/propylene copolymer totally insoluble in xylene at25° C.; and

c) 61% of an amorphous ethylene/propylene copolymer with 30% ofethylene, totally soluble in xylene at 25° C., and having an intrinsicviscosity [η] of 3.1 dL/g.

The composition was obtained by way of sequential polymerization in thepresence of a high-yield and highly stereospecific Ziegler-Nattacatalyst supported on magnesium chloride.

II) Heterophasic composition having the same quantities and componentsof composition (I), but with a MFR of 40 g/10 min and an intrinsicviscosity [η] of fraction (a) of about 1. The composition is obtained byway of chemical cracking of composition (I) with the proper quantity ofTrigonox 101/50 peroxide.

(III) Heterophasic composition having the same quantities and componentsof composition (I), with the difference that it is partiallycross-linked, said cross-linking having been obtained using the dynamiccross-linking process. The intrinsic viscosity [η] of fraction (a) isabout 0.35 dL/g. The cross-linking took place in the presence ofTrigonox 101/50 peroxide and 1,2-polybutadiene (Lithene PH). Thepercentage of gels calculated according to the formula set forth in thedescription is about 38.4. The composition is prepared as described inthe above mentioned European patent application EP-A-633 289, whosedescription is incorporated herein for reference.

IV) Heterophasic composition comprising 32% by weight of a dynamicallycross-linked ethylene/propylene/diene rubber, Dutral TER 537 E2 type,6.5% by weight of crystalline propylene homopolymer, 6.5% by weight of astyrene polymer, and 32% by weight of extender oil.

V) Resin marketed by Mitsui Petrolchemical, reference Milastomer 6030 N:according to our analyses it is a partially dynamically cross-linkedelastomeric thermoplastic composition containing 23% by weight ofextender oil.

VI) Resin marketed by Mitsui Petrolchemical, reference Milastomer 9020N: according to our analyses it is a partially dynamically cross-linkedelastomeric thermoplastic composition without extender oil.

The properties of the above mentioned compositions as reported in table1 have been determined using 120×120 mm plates having a thicknessranging from 1 to 3 mm. Said plates have been obtained by compressionmolding at 200° C., operating first for 3 minutes without pressure, thenfor an additional 3 minutes at 200 bar, and finally cooling the plate to23° C. under pressure.

EXAMPLE 1

In a twin-screw extruder one mixed and extruded at 180° C. 70 parts byweight of composition (II) with 30 parts by weight of composition (III).

The extruded mixture, having a MFR of 36 g/10 min at 230° C./2.16 kg,was then milled at a temperature ranging from −70 to −100° C., thusobtaining a powder with a particle size distribution corresponding towhat is reported in the description.

The milled product was then mixed with 0.7% by weight of Sylobloc 45H(by Grace).

Finally, the powder was used in a slush molding process at 230° C., for20 seconds of contact, 2 minutes of postcure at 230° C., and subsequentcooling, thus obtaining a leather with the dimensions and pinholedensity reported in table 2.

In table 3 are reported the mechanical properties of the compressionmolding plates prepared as described above.

COMPARATIVE EXAMPLE 1 (1c)

Example 1 was repeated, with the exception that instead of compositions(II) and (III), one used composition (II) with a MFR of 40 g/10 min at230° C./2.16 kg.

The dimensions and pinhole density of the leather obtained in thismanner are reported in table 2.

In table 3 are reported the mechanical properties of the compressionmolding plates prepared as described above.

COMPARATIVE EXAMPLE 2 (2c)

Example 1 was repeated, with the exception that instead of composition(III), one used composition (IV). The mixture obtained had a MFR of 28g/10 min at 230° C./2.16 kg.

The dimensions and pinhole density of the leather obtained in thismanner are reported in table 2.

In table 3 are reported the mechanical properties of the compressionmolding plates prepared as described above. The plate appeared sticky.

COMPARATIVE EXAMPLE 3 (3c)

The mixing and extrusion of example 1 were repeated, except that oneused 90 parts by weight of composition (II), and 10 parts by weight ofcomposition (V).

The mechanical properties of the compression molding plates prepared asdescribed above are reported in table 3.

COMPARATIVE EXAMPLE 4 (4c)

Example 3c was repeated, except that one used 70 parts by weight ofcomposition (II), and 30 parts by weight of composition (V).

The mechanical properties of the compression molding plates prepared asdescribed above are reported in table 3.

COMPARATIVE EXAMPLE 5 (5c)

The mixing and extrusion of example 1 were repeated, except that oneused 90 parts by weight of composition (II), and 10 parts by weight ofcomposition (VI).

The mechanical properties of the compression molding plates prepared asdescribed above are reported in table 3.

COMPARATIVE EXAMPLE 6 (6c)

Comparative example 5c was repeated, except that one used 70 parts byweight of composition (II), and 30 parts by weight of composition (VI).

The mechanical properties of the compression molding plates prepared asdescribed above are reported in table 3.

TABLE 1 Compositions Properties I II III IV V VI Flexural 90 70 90 <30<30 ≦200 Modulus (MPa) MFR¹⁾ (g/10′) 0.6 40 6 <1 — — MFR²⁾ (g/10′) — — —— 7 2.3 Tensile strength 22 5.1 11.5 48 5 9 (MPa) Elongation at 850 365510 420 500 600 break (%) Tension set 100% 35 40 30 10 8 30 (%) Shore A,5 sec 90 88 91 60 55 89 (points) Compression 87 95 62 31 34 59 set³⁾ (%)Oil absorption⁴⁾ +346 +205 +266 +90 +253 +250 (weight %) Fogging test %98 78 >90 65 41 95 ¹⁾measured at 230° C./2.16 kg; ²⁾measured at 230°C./5 kg; ³⁾at 70° C. for 22 hours; ⁴⁾ASTM-3, conditions: 166 hours at100° C., measured as weight % diference between the weight before andafter the test.

TABLE 2 Examples and number of maximum pinhole average pinholecomparative examples pinholes/cm² diameter (mm) diameter (mm) 1   <200.08 0.02 1C 1000  0.2 0.03 2C 450 0.15 0.05

TABLE 3 Ex. and Tensile Elongation at Shore A compar. strength break 5seconds Fogging test examples (MPa) (%) (points) (%) 1  8.2 645 89 94 1c5.3 385 88 78 2c 4.9 490 80 81 3c 4.95 325 82 74 4c 4.9 470 78 66 5c 5.4475 87 81 6c 4.5 180 87 87

What is claimed is:
 1. A mixture of elastomeric thermoplasticcompositions comprising (weight percentage): A) from 40 to 90% of aheterophasic polyolefin composition (A) having a melt flow rate(measured according to ASTM-D 1238, condition L) ranging from 20 to 100g/10 min; and B) from 10 to 60% of a partially dynamically cross-linkedheterophasic polyolefin composition (B); where composition (A) comprisesthe following polymer fractions (parts and percentage by weight): a)10-40 parts of an isotactic propylene homopolymer having an isotacticindex greater than 80, or a propylene random copolymer with ethyleneand/or a C₄-C₁₀ α-olefin of formula CH₂═CR where R is a C₂-C₈ alkylradical, with an isotactic index in boiling heptane greater than 80;said fraction having an intrinsic viscosity ranging from 0.8 to 1.3dL/g; b) 0-20 parts of a copolymer fraction containing ethylene,insoluble in xylene at ambient temperature; and c) 40-95 parts of acopolymer fraction of ethylene with propylene and/or a C₄-C₁₀ α-olefinof formula CH₂═CHR, where R is a C₂-C₈ alkyl radical, and optionally asmall quantity of diene; said fraction, soluble in xylene at ambienttemperature, contains ethylene in quantities less than or equal to 35%;and composition (B) comprises the following polymer fractions (parts andpercentage by weight): i) 5-50 parts of an isotactic propylenehomopolymer having an isotactic index greater than 80, or a propylenerandom copolymer with ethylene and/or a C₄-C₁₀ α-olefin of formulaCH₂═CHR, where R is a C₂-C₈ alkyl radical; said copolymer containingmore than 85%, of propylene, and having an isotactic index in boilingheptane greater than 80; said fraction having an intrinsic viscosityranging from 0.15 to 0.6 dL/g; ii) 50-95 parts, of an elastomericpolymer fraction partially cross-linked and partially soluble in xyleneat ambient temperature, containing ethylene, propylene, and/or a C₄-C₁₀α-olefin of formula CH₂═CHR, where R is a C₂-C₈ alkyl radical, and withoptionally a small quantity of diene; said composition (B) comprisingfrom 20 to 92% of a fraction (I) soluble in xylene at ambienttemperature, and containing ethylene, propylene, and/or a C₄-C₁₀α-olefin of formula CH₂═CHR, where R is a C₂-C₈ alkyl radical, andoptionally a small quantity of diene, where the ethylene is present infraction (I) in quantities less than or equal to 35%.
 2. The mixture ofclaim 1, where composition (A) ranges from 60 to 80% by weight.
 3. Themixture of claim 1, where composition (A) ranges from 20 to 40% byweight.
 4. The mixture of claim 1, where composition (A) has a melt flowindex ranging from 30 to 60 g/10 min.
 5. The mixture of claim 1, wherefraction (a) of component (A) has an intrinsic viscosity ranging from0.9 to 1.2 dL/g.
 6. The mixture of claim 5, where fraction (a) ofcomponent (B) has an intrinsic viscosity ranging from 0.2 to 0.5 dL/g.7. A process comprising slush molding a mixture of elastomericthermoplastic compositions comprising (weight percentage): (A) from 40to 90% of a heterophasic polyolefin composition (A) having a melt flowrate measured according to ASTM-D 1238, condition L, ranging from 20 to100 g/10 min; and (B) from 10 to 60% of a partially dynamicallycrosslinked heterophasic polyolefin composition (B); where composition(A) comprises the following Polymer fractions (parts and percentages byweight): a) 10-40 parts of an isotactic propylene homopolymer having anisotactic index greater than 80, or a propylene random copolymer withethylene and/or a C₄-C₁₀ α-olefin of formula CH₂═CHR, where R is a C₂-C₈alkyl radical, with an isotactic index in boiling heptane greater than80; said fraction having an intrinsic viscosity ranging from 0.8 to 1.3dL/g; b) 0-20 parts of a copolymer fraction containing ethylene,insoluble in xylene at ambient temperature; c) 40-95 parts of acopolymer of ethylene with propylene and/or a C₄-C₁₀ α-olefin of formulaCH₂═CHR, where R is a C₂-C₈ alkyl radical, and optionally a smallquantity of diene; said fraction, soluble in xylene at ambienttemperature, contains ethylene in quantities less than or equal to 35%;and composition (B) comprises the following polymer fractions (parts andpercentages by weight): i) 5-50 parts of an isotactic propylenehomopolymer having an isotactic index greater than 80, or a propylenerandom copolymer with ethylene and/or a C₄-C₁₀ α-olefin of formulaCH₂═CHR, where R is a C₂-C₈ alkyl radical; said copolymer containingmore than 85% of propylene, and having an isotactic index in boilingheptane greater than 80; said fraction having an intrinsic viscosityranging from 0.15 to 0.60 dL/g; ii) 50-95 parts, of an elastomericpolymer fraction partially crosslinked and partially soluble in xyleneat ambient temperature, containing ethylene, propylene and/or a C₄-C₁₀α-olefin of formula CH₂═CHR, where R is a C₂-C₈ alkyl radical, andoptionally with a small quantity of a diene; said composition (B)comprising from 20 to 90% of a fraction (I) soluble in xylene at ambienttemperature and containing ethylene, propylene and/or a C₄-C₁₀ α-olefinof formula CH₂═CHR, where R is a C₂-C₈ alkyl radical, and optionallywith a small quantity of a diene; where the ethylene is present infraction (I) in quantities less than or equal to 35%.
 8. The process ofclaim 7, where the diameter of the powder particles is less than 500 μm.9. Laminated product obtained by way of slush molding with the powdersof the mixture of claim
 1. 10. The mixture of claim 1, wherein theisotactic propylene homopolymer a) of heterophasic polyolefincomposition (A) has an isotactic index greater than 90.